1254 GMT February 25, 2018
The outbreak "has reached colossal proportions," said Robert Mardini, the International Committee of the Red Cross's Near and Middle East director, AFP reported.
The collapse of Yemen's infrastructure after more than two years of war.
Saudi Arabia has been incessantly pounding Yemen since March 2015 in an attempt to reinstate former president, Abd Rabbuh Mansur Hadi, a staunch ally of Riyadh, and to undermine the Houthi Ansarullah movement.
Riyadh has, however, failed to reach its goals despite suffering great expense.
The speed at which cholera is spreading in Yemen has slowed some in recent months, but the deadly waterborne disease is far from contained.
"In July we said we feared it would reach 600,000 cases by the end of the year. Now we have reached 647,000 suspected cases already," Mardini told AFP.
"We are now projecting in the worst-case scenario to reach 850,000 by the end of the year," he said, stressing that "it is not under control. It is not contained."
The World Health Organization said earlier this week that 2,065 people had so far perished from the disease.
"The pace was slowing down a bit, but over the past week it went up again," Mardini said, pointing out that there are still around 4,700 suspected cases being registered in the country every day.
The numbers are all the more tragic in light of the fact that cholera is usually an easily preventable disease.
"It is the worst health crisis for a preventable disease in modern times," Mardini told a conference on the sidelines of the UN Human Rights Council.
WHO has warned that the disease has spread rapidly due to deteriorating hygiene and sanitation conditions, with millions of people cut off from clean water across the country.
Less than half of health facilities in the country are functioning, many health workers have not received salaries for nearly a year, and less than 30 percent of the medicines needed in Yemen are reaching the country, Mardini said.